JP5945914B2 - Cleaning agent for removing flux residue - Google Patents

Description

  The present invention relates to a cleaning agent that is a homogeneous solution during storage, becomes cloudy during use, and can suitably remove flux residues.

  The flux residue refers to a flux component that remains in the vicinity of the solder joint when an electronic component such as an IC, a capacitor, or a resistor is soldered to a printed circuit board or the like. As a flux, a rosin base material (hereinafter referred to as a rosin flux) is generally used. It may be applied directly to the electrode, or it may be mixed with solder alloy powder and used as a solder paste. In the manufacture of surface mount substrates, the latter mode is mainstream.

  There are various surface mounting processes using solder paste. For example, solder paste is supplied onto electrodes of a printed circuit board by screen printing or a dispenser, and electronic components are placed on the solder paste. By heating the metal to a melting point or higher, the electronic component and the electrode are joined.

  As described above, since soldering is performed at a high temperature, the rosin-based flux may be scattered from the solder paste and adhere as a residue around the electrode. If the amount of residue is small, there is no particular problem, but if the amount is large, the inspection work and reliability of the surface mount substrate will be adversely affected. On the other hand, the solder joint is inevitably covered with the flux residue film, but corrosion due to acid components (resin acid, activator, etc.) in the residue proceeds, or the adverse effect due to the so-called migration phenomenon in the minute cracks on the residue film surface. Or receive.

  Therefore, the flux residue usually needs to be removed with various cleaning agents, and various products have been proposed in the art as cleaning agents suitable for rosin flux (see, for example, Patent Documents 1 to 3). . The present applicant has also proposed various cleaning agents composed of glycol solvents such as polyoxyalkylene glycol ethers and polyoxyalkylene glycol esters (see, for example, Patent Documents 4 to 7).

  By the way, these cleaning agents are generally used in a state of being heated to about 50 to 60 ° C. in order to increase the cleaning efficiency. However, in order to reduce the viscosity to improve the handling or to suppress the VOC emission. In the cleaning site, the cleaning agent may be diluted with water in advance. However, as a matter of course, the larger the amount of water added, the lower the ratio of the organic solvent that is a cleaning component, so that the flux residue cannot be removed sufficiently.

  In order to solve such a problem, for example, Patent Document 8 proposes a cleaning agent in which three kinds of organic solvents having different SP (solubility parameter) values are combined. This is a uniform solution before blending water, but becomes cloudy by blending and stirring a relatively large amount of water before use, and the flux residue is suitably removed in that state. However, since water must be added each time immediately before use, there is a difficulty in workability. Also, since this cleaning agent is separated into two layers when it is left for a long time after adding water, it is inconvenient in that if the cleaning agent is left, it must be stirred again when it is used next time. It is.

JP-A-6-313195 Japanese Patent Laid-Open No. 7-197095 JP 7-33287 A Japanese Patent Laid-Open No. 5-175541 JP-A-7-97596 Japanese Unexamined Patent Publication No. 7-73893 JP 2002-201492 A JP 2010-189635 A

  An object of the present invention is to provide a novel cleaning agent that is a homogeneous aqueous solution at normal temperature, but becomes cloudy at the time of use (warming) and can suitably remove a flux residue.

  As a result of intensive studies, the present inventor has found that an aqueous solution in which a relatively large amount of water is contained in an organic solvent composed of a predetermined nonionic compound is useful as a cleaning agent for achieving the above-described problem.

That is, the present invention provides at least one branched nonionic compound (1) selected from the group consisting of propylpropylene glycol, propylpropylene diglycol and butylpropylene glycol, and at least one selected from the group consisting of butyl diglycol and hexyl diglycol. A branched nonionic compound of the formula (1) containing 20 to 40% by weight of an organic solvent (A) and 60 to 80% by weight of water (B) comprising the linear nonionic compound (2) And the weight ratio ((1) / (2)) of the linear nonionic compound of formula (2) is 0.5 / 3 to 3 / 0.3, and the cloud point is 20 to 90 ° C. It made using certain aqueous detergent flux residue removal, at least one linear Noni selected from the group consisting of butyl diglycol and hexyl diglycol A flux comprising an organic solvent (A) comprising 20 to 40% by weight of an organic compound (2) and 60 to 80% by weight of water (B) and having a cloud point of 20 to 90 ° C. The present invention relates to a method for cleaning an article, characterized by bringing the cleaning agent into contact with an object to be cleaned to which a flux residue has adhered at a temperature equal to or higher than the cloud point.

  As described above, the cleaning agent of the present invention is a homogeneous aqueous solution at room temperature, but is separated into two layers by heating above its cloud point, and becomes cloudy when further stirred in that state. And it becomes possible to remove a flux residue suitably by this cleaning agent of a cloudy state. In addition, when an amino alcohol is added as an additive to the cleaning agent of the present invention, precipitates are less likely to be generated after cleaning, so that it is suitable for repeated use. In addition, there is an advantage that it can be stored in one liquid state because it is homogeneous at room temperature. Moreover, since it is highly volatile, it is not particularly necessary to provide a subsequent water rinsing step, and the entire process can be simplified. In addition, since the water content is high, VOC emissions are small and can be handled as non-hazardous materials.

The cleaning agent of the present invention is at least one branched nonionic compound (1) selected from the group consisting of propylpropylene glycol, propylpropylene diglycol and butylpropylene glycol, and at least selected from the group consisting of butyl diglycol and hexyl diglycol. An organic solvent (A) comprising 20 to 40% by weight of a linear nonionic compound (2) and 60 to 80% by weight of water (B), and a branched nonionic system of the formula (1) The weight ratio of the compound to the linear nonionic compound of formula (2) ((1) / (2)) is 0.5 / 3 to 3 / 0.3, and the cloud point is 20 to 90 ° C. and that an aqueous solution is composed of at least one linear nonionic compound (2) is selected from the group consisting of butyl diglycol and hexyl diglycol Machine solvent (A) 20 to 40 wt%, and contain water (B) 60-80 wt%, and is to that cloud point using an aqueous solution is 20 to 90 ° C..

Incidentally, if necessary, with the component (A), as a component other than the compound (1) and the compound (2), polyoxyalkylene alkyl ethers, polyoxyalkylene phenols ethers, and polyoxyalkylene alkylphenol ethers, polyalkylene glycol mono Polyalkylene glycol esters such as esters and polyalkylene glycol diesters can be used in combination.

  (B) As an ingredient, ion exchange water, pure water, city water, etc. are mentioned.

  The content of the component (A) and the component (B) in the cleaning agent of the present invention is not particularly limited, but the cleaning agent of the present invention is transparent at room temperature and cloudy at the time of use (at the time of stirring under heating). In consideration of the property and the removal performance of the flux residue, the amount is about 20 to 40% by weight and about 60 to 80% by weight, preferably 25 to 35% by weight and 65 to 75% by weight.

  The cleaning agent of the present invention determines the presence or absence of the cloudiness at a clouding point of 20 to 90 ° C. Here, the cloud point is a term defined in JIS K3211, and in the present invention, it refers to a temperature at which the cleaning agent starts to separate into two layers when the temperature is increased. A cloud point becomes like this. Preferably it is about 25-70 degreeC, More preferably, it is about 30-50 degreeC.

  Although the physical properties of the component (A) are not particularly limited, those having a boiling point of usually 200 ° C. or less, preferably about 140 to 200 ° C., more preferably about 140 to 180 ° C. are preferable from the viewpoint of the drying property of the object to be cleaned.

  In the aqueous solution according to the present invention, various known amino alcohols (C) (hereinafter referred to as component (C)) are included for the purpose of stably dissolving or dispersing contaminants in the cleaning object in the cleaning agent. Can do. Specific examples include amino alcohols having a linear or branched alkyl group (having about 1 to 5 carbon atoms), and examples thereof include n-butyldiethanolamine, ethylethanolamine, and n-butylethanolamine. In addition, the component (C) is particularly effective when the flux residue is derived from a rosin-based flux, and precipitates derived from the flux components are less likely to occur after cleaning. In addition, as the component (C), considering the drying property of the object to be cleaned, those having a boiling point of less than 250 ° C., particularly those having a boiling point of about 150 to 200 ° C. are preferable. The content of the component (C) in the cleaning agent of the present invention is not particularly limited, but is usually about 0 to 5% by weight, preferably 0.1 to 1% by weight when the aqueous solution according to the present invention is 100% by weight. It is a range.

  The method for cleaning an article of the present invention is characterized in that the cleaning agent of the present invention is brought into contact with an object to be cleaned to which a flux residue adheres at a temperature equal to or higher than the cloud point. The object to be cleaned is not particularly limited as long as a flux residue, specifically, a rosin flux residue adheres thereto. For example, an electronic component such as an IC, a capacitor, or a resistor may be surface-mounted on a printed board with a solder paste containing a rosin flux. The rosin flux is not particularly limited as long as rosin is used as a base material, and may contain various activators, thixotropic agents, additives, and the like.

  Means for bringing the cleaning agent of the present invention into contact with an object to be cleaned is not particularly limited, and examples thereof include various methods such as immersion cleaning, shower cleaning, ultrasonic cleaning, and submerged jet cleaning. Moreover, a cloudy state is achieved by using various mixing means together at the time of washing | cleaning.

Moreover, the to-be-cleaned object after washing | cleaning is attached | subjected to a drying process. The water rinsing step after drying is not particularly necessary, but when provided, the compound (1) and the compound (2) are removed with rinsing water by setting the rinsing temperature below the cloud point of the cleaning agent of the present invention. It becomes easy.

  Hereinafter, the present invention will be described in more detail through examples, but the scope of the present invention is not limited to these examples. Parts are based on weight.

<Preparation of cleaning composition>
Example 1
A cleaning composition was prepared by placing 30 parts of propylpropylene glycol as component (A) and 70 parts of pure water as component (B) into a beaker and stirring well.

Examples 1-5, Comparative Example 1
A cleaning composition was prepared in the same manner as in Example 1 except that each component was changed to Table 1. The numbers in the table indicate the number of copies.

<Preparation of test plate for cleaning test>
A ring-shaped lead-free solder alloy was placed on a commercially available copper plate (2.0 cm × 4.0 cm × 0.3 mm). Next, three drops of a commercially available acrylated rosin (trade name “KE-604”, manufactured by Arakawa Chemical Industries, Ltd.) and isopropyl alcohol (nonvolatile content 80%) were injected into the ring with a dropper. The copper plate was then placed on a hot plate and heated at 250 ° C. to melt the lead-free solder alloy, leaving a dome-shaped solder alloy covered with the flux residue. The copper plate thus obtained is used as a cleaning test substrate A.

  Instead of the flux solution, a flux solution made of Arakawa Chemical Industries, Ltd., lead-free solder flux (trade name “A59-26-35”; KE-604 as base rosin and other various active agents) and isopropyl alcohol A copper plate with a solder alloy was prepared by the same method as above using (nonvolatile content 80%). This is designated as a cleaning test substrate B.

<Cleaning test>
The cleaning composition of Example 1 was put in a 100 mL beaker, heated to 60 ° C., stirred with a stirrer, and suspended. Next, the cleaning test plates A and B were immersed in the cleaning composition in that state, the time until the flux residue was dissolved was measured, and the cleaning power was evaluated according to the following criteria. The cleaning powers of the cleaning liquid compositions of other examples and comparative examples were similarly evaluated.

Less than 3 minutes ... ◎
3 minutes or more, less than 4 minutes ... ○
4 minutes or more and less than 5 minutes ... △
5 minutes or more ×

<Confirmation of precipitate>
After the cleaning test, stirring was stopped, the appearance of the cleaning liquid was maintained while maintaining the temperature, and the presence or absence of precipitates was visually determined based on the following criteria.

No precipitate ... ○
There is a deposit ... ×

PFG: propyl propylene glycol PFDG: propyl propylene diglycol BDG: butyl diglycol HeDG: hexyl diglycol MEM: ethyl ethanolamine

Claims (5)

At least one branched nonionic compound (1) selected from the group consisting of propylpropylene glycol, propylpropylene diglycol and butylpropylene glycol, and at least one linear nonion selected from the group consisting of butyldiglycol and hexyldiglycol A branched nonionic compound of the formula (1) containing 20 to 40% by weight of an organic solvent (A) comprising the compound (2) and 60 to 80% by weight of water (B) and the formula (2) Using an aqueous solution having a weight ratio ((1) / (2)) to a linear nonionic compound of 0.5 / 3 to 3 / 0.3 and a cloud point of 20 to 90 ° C. A cleaning agent for removing flux residue. Contains 20 to 40% by weight of an organic solvent (A) composed of at least one linear nonionic compound (2) selected from the group consisting of butyl diglycol and hexyl diglycol, and 60 to 80% by weight of water (B). And the cleaning agent for flux residue removal which uses the aqueous solution whose cloud point is 20-90 degreeC. The cleaning agent for removing a flux residue according to claim 1 or 2 , wherein the boiling point of the organic solvent (A) is 200 ° C or lower. Furthermore, the cleaning agent for flux residue removal in any one of Claims 1-3 containing amino alcohol (C). A cleaning method for an article, comprising bringing the cleaning agent according to any one of claims 1 to 4 into contact with an object to be cleaned at a temperature equal to or higher than the cloud point.